The present contribution explores the capability and benefits of the technique of ¿in situ¿ thermally assisted pyrolysis-silylation GC-MS using hexamethyldisilazane as derivatisation reagent. This technique has the analytical advantage of having high sensibility and reducing considerably the size of the samples tested. For this reason, it is especially suitable for detecting the presence of organic compounds in objects highly deteriorated such as rock art and buried archaeological remains. The study has been focused on the identification of the binding médium present in several rock paintings found in shelters of the Peruaçu valley (Minas Gerais, Brazil) as well as in the characterization of the adhesive used in the gilding decoration of several glazed tiles from the Takht-e Soleyman palaces (Iran) (13th-15th centuries, Ilkhanian period). The results obtained in the analysis of the series of samples from Peruaçu rock paintings evidenced that a fatty substance of animal origin was used as binding medium of these paintings. On the other hand, linseed oil was identified in the series of samples excised of the glazed ceramics from Takht-e Soleyman. Interestingly, this material has been preserved in an extraordinary low degree of oxidation due to the protective effect of the metallic layer.